Critic says dredging Big Pass will harm Siesta beach

Aerial photo taken in Oct. 2012 showing Lido Key in the background, Big Pass and Siesta Key on the right. The view is from the south, looking north. The sand shoal at the mouth of the pass and offshore of Siesta Key is clearly visible in the foreground.

Published: Monday, December 2, 2013 at 6:03 p.m.

Last Modified: Monday, December 2, 2013 at 6:03 p.m.

LIDO KEY - A plan to dredge Big Sarasota Pass could disrupt the supply of white sand to Siesta Key beaches as well as ruin a Sarasota County park at the south end of Lido, says the county's former environmental services director.

Facts

INTERESTED?

WHAT: A meeting of the Siesta Key Association.

WHO: Army Corps of Engineers project manager Milan Mora will answer questions about the dredging of Big Sarasota Pass and the renourishment of Lido Key beaches.

Rob Patten is not alone in sounding the alarm over a beach renourishment plan introduced by the U.S. Army Corps of Engineers on Oct. 22 at a joint meeting of the Sarasota city and county commissions.

The corps proposes pumping sand from a shoal, or sandbar, in Big Pass onto a critically eroded shoreline to the north on Lido Key, where the Gulf threatens condos and hotels. It would be the first time Big Pass has ever been dredged. The plan also calls for erecting three rock structures, called groins, on the South Lido beach to keep sand from entering the pass.

The project would extend 50 years, alternating the dredging every five years, first at Big Pass, then at New Pass. Project manager Milan Mora estimates the cost at $22.7 million for the first phase, 63 percent coming from the federal government, the rest from the state and from tourist development taxes.

Most of the project area falls within City of Sarasota boundaries. If the state Department of Environmental Protection approves it, the city sees a chance to obtain sand at minimal cost for Lido Beach.

But Patten and others see problems, big ones.

The shoal scheduled for dredging protects Siesta Key from erosive wave action and supplies much of the white sand that helped Siesta Beach earn its place as the country's No. 1 beach in 2011.

“It will stick up and destroy the beach as we know it,” he says. “I can't understand why they wouldn't have a thorough vetting of all the issues, many of which are brought up in the corps' own reports.”

In the mid-1990s, a similar plan that would have pumped sand from Big Pass to the city of Venice was abandoned after the risks became known.

As noted in a January 1994 review by David Aubrey of Woods Hole Oceanographic Institution and Robert Dolan of the University of Virginia: “Siesta Key's stability and low erosion rates are linked both directly and indirectly to the Big Sarasota Pass ebb shoal's capacity to shelter the key from high energy waves and storm forces, as well as the sand transport that occurs in conjunction with the shoal, the pass and the key.

“If the dredging planned by the U.S. Army Corps of Engineers is carried out, this will modify the wave and storm protection, and alter the sediment supply to the onshore beaches.”

The groins also pose a threat, Patten says.

Comprising rocks weighing tons, they will measure 350, 460 and 500 feet in length and 80 feet in width at their bases. They will be installed, then covered for the most part with sand from the pass. However, Patten points out, wind and wave action could expose the groins in a short time, leaving unsightly barriers at a popular park.

Groins and other types of armoring are also notorious for gouging the beaches down current from them. In this case, those beaches would be on Siesta Key.

Patten, a pilot, says he often inspects the results of beach armoring from the air. “I am waiting still to find a groin field that doesn't have considerable down-drift erosion,” he says.

Peter van Roekens happens to live on Siesta Key, but he also leads a coalition of boaters against the project. As a member of the Sarasota Yacht Club, he also measures and records channel depths in Big Pass.

He says that although the channel wanders and requires local knowledge to navigate, it seems to maintain about a 5.5-foot clearance at mean low water. That makes it navigable under most conditions.

Van Roekens fears that erecting groins and tampering with the natural accumulation of sand in the shoal could make navigation even trickier.

The corps stands by its computer modeling as the answer to worries about navigation, damage to the county park and down-current erosion.

The modeling, which predicts the interaction of water and sand in various scenarios, indicates that the effect on Siesta Key beaches will be minimal, corps project manager Milan Mora says.

If the city and corps intend to establish a long-term renourishment project, they all but have to use the shoal. An offshore supply of sand identified in a 2002 study no longer meets state criteria for replenishing Lido Beach. Instead of yielding an estimated 1.8 million cubic yards of sand, that site can now provide only 500,000 cubic yards.

The project calls for 1.1 million cubic yards to be dumped onto Lido Key.

Neighboring New Pass, which the corps has previously dredged as a navigation project, also falls short as a supply source, Mora says. It can provide no more than 300,000 to 400,000 cubic yards at a time. That is enough for the five-year renourishments but not the initial one.

The groins also form an integral part of the project by anchoring all the sand deposited to the north, Mora says. Without them, the models predict dredging would have to occur every two to 2.5 years instead of every five, he says.

As the proponents and the skeptics start to galvanize their positions, the dredging/renourishment could easily turn into a Lido-Siesta, city-county brouhaha.

“I think there are issues that are important, that need to be thoroughly vetted, but as long as there's a project, shouldn't we take advantage of it?” Sarasota City Commissioner Susan Chapman asks.

“The groins are my biggest worry. They typically cause erosion downshore,” says County Commission Nora Patterson. “I'm not opposed to nourishing beaches that require it. And I do know the shoal has grown. I worry we're going to steal sand from Siesta and double the problem.”

County Commissioner Christine Robinson has similar concerns, compounded by the issue of whether the county has much say in what happens.

The groins would be in what is technically a county park, but because the sand has accreted along the shore over the years, it is unclear where the seaside boundary lies. The groins might be on state-controlled land.

Robinson said she has plenty of questions, some of which she hopes will be answered during a County Commission workshop scheduled for Jan. 28.

At the very least, the city or county should hire independent coastal engineers and other scientists to review the corps' methodology and assumptions, the opponents say.

“Our side wants a peer review and a public hearing,” van Roekens says. “It's hard to see how anyone could object to that.”

<p><em>LIDO KEY</em> - A plan to dredge Big Sarasota Pass could disrupt the supply of white sand to Siesta Key beaches as well as ruin a Sarasota County park at the south end of Lido, says the county's former environmental services director. </p><p>Rob Patten is not alone in sounding the alarm over a beach renourishment plan introduced by the U.S. Army Corps of Engineers on Oct. 22 at a joint meeting of the Sarasota city and county commissions.</p><p>The corps proposes pumping sand from a shoal, or sandbar, in Big Pass onto a critically eroded shoreline to the north on Lido Key, where the Gulf threatens condos and hotels. It would be the first time Big Pass has ever been dredged. The plan also calls for erecting three rock structures, called groins, on the South Lido beach to keep sand from entering the pass.</p><p>The project would extend 50 years, alternating the dredging every five years, first at Big Pass, then at New Pass. Project manager Milan Mora estimates the cost at $22.7 million for the first phase, 63 percent coming from the federal government, the rest from the state and from tourist development taxes.</p><p>Most of the project area falls within City of Sarasota boundaries. If the state Department of Environmental Protection approves it, the city sees a chance to obtain sand at minimal cost for Lido Beach.</p><p>But Patten and others see problems, big ones.</p><p>The shoal scheduled for dredging protects Siesta Key from erosive wave action and supplies much of the white sand that helped Siesta Beach earn its place as the country's No. 1 beach in 2011.</p><p>“This is fraught with unanswered questions,” says Patten, who managed environmental services from 2001-06, directed coastal zone management from 1979-85 and now runs a beach restoration company.</p><p>“It will stick up and destroy the beach as we know it,” he says. “I can't understand why they wouldn't have a thorough vetting of all the issues, many of which are brought up in the corps' own reports.”</p><p>In the mid-1990s, a similar plan that would have pumped sand from Big Pass to the city of Venice was abandoned after the risks became known.</p><p>As noted in a January 1994 review by David Aubrey of Woods Hole Oceanographic Institution and Robert Dolan of the University of Virginia: “Siesta Key's stability and low erosion rates are linked both directly and indirectly to the Big Sarasota Pass ebb shoal's capacity to shelter the key from high energy waves and storm forces, as well as the sand transport that occurs in conjunction with the shoal, the pass and the key.</p><p>“If the dredging planned by the U.S. Army Corps of Engineers is carried out, this will modify the wave and storm protection, and alter the sediment supply to the onshore beaches.”</p><p>The groins also pose a threat, Patten says.</p><p>Comprising rocks weighing tons, they will measure 350, 460 and 500 feet in length and 80 feet in width at their bases. They will be installed, then covered for the most part with sand from the pass. However, Patten points out, wind and wave action could expose the groins in a short time, leaving unsightly barriers at a popular park.</p><p>Groins and other types of armoring are also notorious for gouging the beaches down current from them. In this case, those beaches would be on Siesta Key.</p><p>Patten, a pilot, says he often inspects the results of beach armoring from the air. “I am waiting still to find a groin field that doesn't have considerable down-drift erosion,” he says.</p><p>Peter van Roekens happens to live on Siesta Key, but he also leads a coalition of boaters against the project. As a member of the Sarasota Yacht Club, he also measures and records channel depths in Big Pass.</p><p>He says that although the channel wanders and requires local knowledge to navigate, it seems to maintain about a 5.5-foot clearance at mean low water. That makes it navigable under most conditions.</p><p>Van Roekens fears that erecting groins and tampering with the natural accumulation of sand in the shoal could make navigation even trickier.</p><p>The corps stands by its computer modeling as the answer to worries about navigation, damage to the county park and down-current erosion.</p><p>The modeling, which predicts the interaction of water and sand in various scenarios, indicates that the effect on Siesta Key beaches will be minimal, corps project manager Milan Mora says.</p><p>If the city and corps intend to establish a long-term renourishment project, they all but have to use the shoal. An offshore supply of sand identified in a 2002 study no longer meets state criteria for replenishing Lido Beach. Instead of yielding an estimated 1.8 million cubic yards of sand, that site can now provide only 500,000 cubic yards.</p><p>The project calls for 1.1 million cubic yards to be dumped onto Lido Key.</p><p>Neighboring New Pass, which the corps has previously dredged as a navigation project, also falls short as a supply source, Mora says. It can provide no more than 300,000 to 400,000 cubic yards at a time. That is enough for the five-year renourishments but not the initial one.</p><p>The groins also form an integral part of the project by anchoring all the sand deposited to the north, Mora says. Without them, the models predict dredging would have to occur every two to 2.5 years instead of every five, he says.</p><p>As the proponents and the skeptics start to galvanize their positions, the dredging/renourishment could easily turn into a Lido-Siesta, city-county brouhaha.</p><p>“I think there are issues that are important, that need to be thoroughly vetted, but as long as there's a project, shouldn't we take advantage of it?” Sarasota City Commissioner Susan Chapman asks.</p><p>“The groins are my biggest worry. They typically cause erosion downshore,” says County Commission Nora Patterson. “I'm not opposed to nourishing beaches that require it. And I do know the shoal has grown. I worry we're going to steal sand from Siesta and double the problem.”</p><p>County Commissioner Christine Robinson has similar concerns, compounded by the issue of whether the county has much say in what happens.</p><p>The groins would be in what is technically a county park, but because the sand has accreted along the shore over the years, it is unclear where the seaside boundary lies. The groins might be on state-controlled land.</p><p>Robinson said she has plenty of questions, some of which she hopes will be answered during a County Commission workshop scheduled for Jan. 28.</p><p>At the very least, the city or county should hire independent coastal engineers and other scientists to review the corps' methodology and assumptions, the opponents say.</p><p>“Our side wants a peer review and a public hearing,” van Roekens says. “It's hard to see how anyone could object to that.”</p>